Techno Press

Advances in Environmental Research   Volume 3, Number 3, September 2014, pages 187-197
Activation of persulfate by UV and Fe2+ for the defluorination of perfluorooctanoic acid
Zhou Song, Heqing Tang, Nan Wang, Xiaobo Wang and Lihua Zhu

Abstract     [Full Text]
    Efficient defluorination of perfluorooctanoic acid (PFOA) was achieved by integrating UV irradiation and Fe2+ activation of persulfate (S2O82-). It was found that the UV-Fe2+, Fe2+-S2O82-, and UV-S2O82- processes caused defluorination efficiency of 6.4%, 1.6% and 23.2% for PFOA at pH 5.0 within 5 h, respectively, but a combined system of UV-Fe2+-S2O82- dramatically promoted the defluorination efficiency up to 63.3%. The beneficial synergistic behavior between Fe2+-S2O82- and UV-S2O82- was demonstrated to be dependent on Fe2+ dosage, initial S2O82- concentration, and solution pH. The decomposition of PFOA resulted in generation of shorter-chain perfluorinated carboxylic acids (PFCAs), formic acid and fluoride ions. The generated PFCAs intermediates could be further defluorinated by adding supplementary Fe2+ and, S2O82- and re-adjusting solution pH in later reaction stage. The much enhanced PFOA defluorination in the UV-Fe2+-S2O82- system was attributed to the fact that the simultaneous employment of UV light and Fe2+ not only greatly enhanced the activation of S2O82- to form strong oxidizing sulfate radicals (SO4•-), but also provided an additional decarboxylation pathway caused by electron transfer from PFOA to in situ generated Fe3+.
Key Words
    perfluorooctanoic acid; synergism; persulfate; UV; ferrous ions
(1) Zhou Song, Heqing Tang:
Key Laboratory of Catalysis and Materials Science, The State Ethnic Affairs Commission and Ministry of Education, College of Chemistry and Materials Science, South-Central University for Nationalities, 182 Minyuan Road, Hongshan District, Wuhan, P.R. China;
(2) Zhou Song, Nan Wang, Xiaobo Wang, Lihua Zhu:
College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Hongshan District, Wuhan, P.R. China.

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